1. Field of the Invention
This invention relates to oral compositions and their use in a method for controlling dental plaque.
2. The Prior Art
Dental plaque forms as a film on teeth. It is a dense microbial layer formed as a product of microbial growth. The closely matted microorganisms in plaque are embedded in a proteinaceous matrix of uncertain origin that is generally considered to be at least partially salivary. The microorganisms involved are mainly coccoidal, this is especially true in early plaque which in the mouths of some persons change to filamentous organisms after a few days.
It is believed that dental plaque precedes calculus. Also, it is generally accepted by dental experts that clinical supra-gingival calculus (tartar) is a type of dental plaque which is mineralized with a formation of a calcium phosphate crystalline-structure. It will be apparent therefore that the incidence of calculus formation can be reduced by employing dental compositions which reduce or prevent the deposition of plaque.
Dental plaque has been observed to form following dental prophylaxis. This plaque was attributed to bacteria acquired from the saliva where they had resided and remained unaffected by the prophylaxis treatment. Plaque may form on any part of the tooth surface. It is found particularly at the gingival margin, and on the surface of dental calculus. Plaque, like calculus, is considered to be a prime causative factor in peridontal disease. Gingivitis and other types of gingival disease arise when plaque is not controlled.
A wide variety of chemical agents have been suggested to retard plaque formation and the resulting plaque diseases. Mechanical removal of plaque is attempted with oral hygiene measures, but average toothbrushing only partially results in plaque removal. Therefore, the additional use of chemical antibacterials inhibiting plaque formation in inaccessible dental areas is indicated. Germicides which have been proposed include phenolic compounds, halogenated bis-phenols (e.g. hexachlorophene), organic mercurials, hydroxyquinolines, iodine esters of hydroxybenzoic acids, chloramine T, and surface active compounds (detergents) among others. These germicides are excellent laboratory disinfectants but are relatively poor in vivo plaque inhibitors.
The antiplaque properties of metal ions were mentioned as early as 1940 (Hanke, M. T.: "Studies on the local factors in dental caries. I. Destruction of plaque and retardation of bacterial growth in the oral cavity". JADA 27, 379, 1940). U.S. Pat. No. 1,593,485 refers to zinc phenolsulfonate as a bactericide. The use of zinc oxide or zinc phosphate for the stabilization of dental creams is described in U.S. Pat. No. 3,622,662. Zinc oxide and zinc sulphate are described in U.S. Pat. No. 3,624,199 for the same purpose. Effervescent antiplaque tablets containing zinc chloride are described in U.S. Pat. No. 3,888,976.
Antiplaque and anticalculus effects have been claimed in U.S. Pat. No. 4,146,607 for zinc ions combined with tetradecylamine. U.S. Pat. No. 4,339,432 discloses mouthwashes combining zinc and glycine. Combinations of zinc salts and enzymes are reported for their oral activity in U.S. Pat. No. 4,082,841.
Antiplaque effects of oral rinses containing zinc salts and antibacterials have been reported in U.S. Pat. No. 4,022,880. Among the antibacterials listed in this patent are halogenated salicylanilides, halogenated carbanilides, halogenated bisphenols, alkylbenzoyl acrylates, quaternary ammonium compounds, thiuram sulfides, dithiocarbamates, antibiotics, halogenated diphenol ethers, halogenated anilides of thiophene carboxylic acids, and chlorhexidines. U.S. Pat. No. 4,522,806 discloses the antiplaque activity of zinc salts in combination with hexetidine.
As may be noted from the foregoing description of the prior art, zinc salts and combinations of these salts with antibacterials and other actives have been shown to be inhibitors of dental plaque. There are, however, taste, formulation and safety difficulties associated with zinc salts and many of their coactives. It has also been found desirable to obtain antiplaque compositions with increased efficiency.
Accordingly, it is an object of the present invention to provide an oral composition of improved effectiveness against dental plaque.
Another object of this invention is to provide antiplaque compositions of improved taste and better formulation compatibility.
A further object of this invention is to provide a method for reducing plaque and the resultant calculus formed in the oral cavity.